Fourteen research projects concern control processes in normal and neoplastic cells. Seven of these consider the nature of cell membranes: The structure of integral glycoproteins associated with solute transport in human erythrocytes; surface proteins in early chick embryos related to cell adhesion and proliferation in cultures of myoblasts, neural retina, glial cells, and neurons of the telencephalon; factors associated with expression of mouse lymphocyte TL antigens; insulin binding proteins in rat hepatocytes; the differentiation of granulocytes and erythrocytes in cultures of mouse and human bone marrow. Three projects consider DNA synthesis, recombination, and repair: mechanisms of DNA inhibition by aranucleosides and nalidixic acid in E. coli and B. subtilis; DNA repair in human lymphocytes following treatment with MMS, acetoxy-AAF and the diol epoxide of benz-pyrene; development of a cell-free system for studies on DNA repair; analysis of mutants of the yeast S. cerevisiae involve RNA transcription and translation: the characterization of RNA binding proteins from mouse liver and hepatoma nuclei, and of specific proteins from rat ribosomes; processes of tRNA thiolation and the role of thyroxine in influencing the thiolating enzyme sulfurtransferase in cerebrum of newborn rats; stages in insulin biosynthesis in cultures of human and rat beta cell tumors, with reference to preproinsulin message and its control.